Optical projection systems and projection-exposure apparatus comprising same
US5959784A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 24, 1997 |
| Grant date | Sep 28, 1999 |
| Priority date | — |
| Expiry date | Apr 24, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70358
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The invention pertains to optical projection-exposure apparatus for photolithography that can focus a pattern defined by a mask onto a non-flat substrate. In one embodiment, piezoelectric elements are used as an actuator for adjusting the optical path length between the mask and the substrate. A first reflector reflects a light flux transmitted by the mask. A telecentric optical system then forms an image of the mask in a focal plane. A second reflector reflects the light flux from the telecentric perpendicularly onto the substrate. The actuator moves the first or second reflectors, changing the optical path length of the light flux. A focus sensor detects the height of the sensitized surface of the substrate in a direction perpendicular to the sensitized surface of the substrate and thereby provides a focus signal to the actuator. The actuator then moves the focal plane to the sensitized surface.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.